Or someone added a 1N34 or a 1N60 or something so as to use a plain pentode for the audio preamp. The 1N34: 1946! 1N60 is still maybe the most sensitive detector, 1956. Not much different to 1N34.
Germanium diodes existed during WWII.
TVs used EAA and EB parts because they were cheaper. The Battery valve AM/FM sets used semiconductor diodes for FM (DAF96 on AM) long before Mains valve sets, due to filament power saving, even the first ones using a DC90 VHF-Mixer. Later the DF97 triodiesed were used.
There are Magic eyes with accessible amps, the EM34 and the single triode cousins aren't. The EAM86 magic eye even has a diode!
https://www.radiomuseum.org/tubes/tube_eam86.html
I used a Russian 1j24b and an 1N60 to replace a DAF96 as an experiment. Two 1j24b Pentodes wired like a Triode/Pentode will replace a Triode /Hexode, Heptode or Octode with no changes to the original circuit, just an adaptor.